Telephone-exchange system



Oct. 16, 1923. l R. s. BAiLEY TELEPHONE EXCHANGE SYSTEM Filed oct. 15 [1919 ffy W AW lto Patented Oct. 16, 1923. i

UNITE smTESPArENr orifice t RAND s.` BAILEY,y or MCNTCLAIR, NEW JEEsEY, AssIGNoRi'ro AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION or NEW YORK; i

l TELEPHONE-EXCHANGE SYSTEM.

Application filed October 15, 1919. `Serial No. 330,876.

To all fic/0m t may concern: i

Be it known that I, RAND SQ BAILEY, residing at Montclair, in the county ot Essex and State ot' New Jersey, have 'invented certain mpi'oveiiients in Teleplioiie-Ex change Systems, o't which the following is a specification. i

This inventionrelates to telephone exchange systems, and more particularly to such systems in which connections between telephone lines teri'iiinatinpT at manual and automatic exchanges are established by way ot trunk circuits, over `which automatic switches are controlled 'trom the manual. rexchange for effecting` connections between the trunk circuits and telephone lines at the automatic exchange.

The object of this invention is the production of an improved system of this character by which the" operators at a manual exchange vmay control over the trunk circuit the automaticswitches provided at the automatic exchange, for establishing connections between the trunkcircuits and the telephone lines.

In accordance with the various features of this invention, thetransinission ot selecting impulses over the trunk circuit from Athe manual exchange to the automatic exchange is effected by intermittently inter# ruptiiig vthe continuity ot arbridgi'e ot' the talking conductors ot the trunk circuit by means ot a relay bridged across the talking Coiiductors and controlled. byy an im`` pulse sending' device at the manual. exe change, the bridge being' established in the first instanceby a relay responding' to the connection of a link circuit with tli-e trunk circuit. i y

For a more complete understanding ot' this in vcntion retcrence should be had tothe tollowina' description considered in coniiection with the accoii'iiianying drawing which illustrates one embodiment ot the invention,

There is shown in the drawing` a telephone line A termin-ating at a manual ex'A change. where it may be connected with the link lcircuit B in any suitable and well known manner,` The calling end ofthe link circuit B may be connected with the trunk circuit C extending from tlieinanual to an automatic exchange.` at` which are provided the usual selector and connector' switches ior effecting' connection between the trunk circuit and telephone lines, such as D, terminating at the automatic exchange. At the automatic exchange the f trunk circuit is niultipled to jack terminals at a toll switchboard at which is located ay link `circuit E, by means yof which connection may be established with the `trunk circuit and signals at ythe manual exchange controlled from the toll switchboard.` The apparatus shown to the `lett ot the dotted line l- -l is located at the manual exchange, while -that shown to their-ight of the d`otted line is located at the automatic exchange. such kthat it is believed a clearfunderstanding thereof will be obtained from a description of the loperation of the system shown The nature of this invention is in the drawing and it will vbe so described. f

`The subscriberat the station on telephone line A having initiated a call and the answering end of the link circuit B having,y 'been associatedl therewith in any well known manner, the operator actuates listening key 1` minates at the automatic exchange, the operator inserts calling plug Got the link circuit B` into jack 7 of the trunk circuit C.

The relays S `and 9 thereupon operate over a circuit from battery through the winding ot relay` 8, sleeve contacts ot' the plug' t3 and the jack l7 and both windings ot relay 9 vto ground. The operation 'ot relay 8 closes a normally open cont-actin the tip'conductor ot thelink circuit B. i

Relayl() operates uponthe energization oi' rela-y 9 closing a normally open contact "in the tip talkingV conductor of the trunky circuit C, and operating busy signal llassociated with thelmultiple jack. Relay 10 in operatingr causes the energization of relay 1:2 over a circuit Jfrom battery through the windingot relay 12, left-hand Contact of relay 13 and the right-hand alternate Contact ot relay l0 to ground. Relay 12 in operatincj 'closes its right-hand Contact, thereby establishing a short circuit lor impedance coil 14, i, v 1i The energization of relayS causes the operation of relay 13 overa circuit from battery through theflett-hand winding of battery feed coil 20, windingof supervisory re lay 21, lower normal contact oi' ringing key 22, lower normal contact oi relay 23, ring contacts of the plug 6 and the jack T, winding kot relay 13, tip contacts of the jack and the plug 6, upper normal contact of relay 23, upper normal contact of ringing key 227 alternate contact of relai 8 and the right-hand winding o'l battery feed coil 2O to ground. Relay 13 is oi high impedance to talking currents and is of such high resstancethat supervisory relay 21 does not operate when .connected in series therewith. Relay 21 will operate, however7 when the plug` 6 of the cord circuit B is connected to-y thejaciof a circuit (not shown), which has a low resista-nce bridge across the talking conductors. Relay 13 in operating establishes a bridge across the talking'conductors ot the trunk circuit which may loe traced trom the tip talking conductor through the right-hand Contact of relay 12 and the right-hand contact ot relay y13 to the ring talking conductor. The operation ot relay 13, however, opens the energ'aing circuit ot slow release relay 12 which thereby becomes deenergized and when its armatures are ttul-ly released, opens the short circuit about Vthe impedance Vcoil 14 which is thereby included `in the bridge previously traced.

Upon the establishment oit this bridge V across the talking conductors ot' the trunk circuit', impulse response relay 30 operates over a circuit from battery through the left `'han'd winding of impulse response relay 30, inner right-hand Contact ot cut-ott relay 31, right-hand contactot relay 13, impedance coil 14C.. outer right-hand contact ot cutoii" relay 31 1and the right-hand windinrl of impulse response relay 30 to ground. This impulse response relay 30 controls the usual motor magnets and contro-l mechanism for the selector and connector switches provided at the automatic exchange for effecting connection between trunk circuits and the telephone lines terminating ther-eat. Condensers 32 and provided in the tip and ring talking conductors of the trunk circuit divide the talking conductors into inner and outer sec-tions and serve to prevent the flow of `current from the link circuit B over the trunk circuit to the automatic exchange and also to prevent the flow oi current tro-m the automatic exchange to the link circuit when connected with the trunk circuit.

ln order that one ot the telephone lines terminating at the automatic exchange. when connection therewith isdesired. may be selected `and the trunk circuit C connected therewith., there is provided an impulse sending device which may be connected with the link circuit B through the operation ot relav 23 uipon the actuation of key 4.0. The actuation of 'key 40 causes the operation of relay 23 which opens the tip and ring conductorsot the link circuit B and bridges the opcrators sending device l1 across the talkconductors ot the link circuit connected with the contacts o1v the plug G. vThe closure ol" the lower contact of relay 23 lights the sending device pilot lamp 42. The sending device e1 is connected with the talking conductors before the continuity thereof is interrupted so that relay 13 remains enerthrough the contacts of the sending dc .'ice. Relay 13 is deenergized upon each opening of the sending device contact. Upon the rst such opening of the contact of sending device 41 and deenergization ot relay 13, relay 12 operates to establish a short circuit about the impedance coil 1-1 and the opcnn g ol" the right-hand contact of relay i terrupts the bridge across the talking conductors of the trunk circuit causing the release ot' the impulse response relay 30. Relay 12 is made slow in releasing so that the short circuit of the impedance coil 14 will be maintained during the short intervals that relay 13 is energized when the sending device is transmitting impulses.

Impulse response relay 30 controls the motor magnets of the selector' and connector switches at the automatic exchange. .fitter the sending ot the proper number of impulses relay 13 remains energized and re- Y lay 12 releases its armatures removing the short circuit of the impedance coil 14. The trunk circuit C is connected with the tele phone line D by means ot' the switches 43 and 44C controlled by the motor magnets and control apparatus associated with the impulse response relay 30. The impedance coil 14C which is ot high impedance to talkinf-I. currents so that it has no appreciable eifect thereon is provided orcontrolling supervisory apparatus as will more fully hereinafter appear. The purpose oft short-circuitinc this impedance coil 14 is to increase the signaling lrange and to prevent anv disturbances.v due to inductive action of this impedance coil were it left in the circuit while transmit-ting the impulses. After the impulses have been transmitted, the operator may restore the key 410 to its normal posi tion, whereupon relay23 releases to reestablish the continuity ot the talking conductors ot' the link circuit and to disconnect thc operators impulso sending device fil 'from these conductors.

The station on telephone line D may be.

lill" signalled in any usual and well known -manmanual exchange by therestoration of the' ing key 47 is actuated and then restored to its normal position. The insertion of the plug 45 into the 4G causes the operationv of relay 56 and cut oftl relay 3l. The operation of relay 56 causes supervisory lamp 52 to be lighted and to remain lighted until the operator at the manual exchange answers as Will more fully hereinafter appear. The operation of cut off relay 3l disconnects impulse response relay 30 from the trunk circuit C. During the time that the ringing key 47 is actuated, ringing response relay 48 is energized over a circuit from a source of ringing current 49 through the lower alternate contact of ringing key 47, ring'contacts of the plug 45 and the jack 46, condenser 33, normal contact of relay 48 and Winding thereof and the normal contact of relay 10 to ground.` Ringing re,

spon'se relay'54 also energizes but performs no useful function at` this time.

Relay 48 in operating` completes a lock c ingcircuit forr itself from battery `through the Winding of slow release relay l2, right! hand alternate contact of relay 48and Winding thereof and the normal contact of relay lO to Iground. Relay `48 in operating closes its left-hand contact, thereby causinglamp 50 tobe lighted. .Relay l2 in clos-- ing its right-hand contact establishes 'the short circuit for iiniiedance coil`l4,`and in closing' its left-hand conta/t causes busy signal '1 -l to be operated over a circuit from battery through the winding of the busy sig nal il. left-hand cinitact of relay l2, and the normal contact of relaylO to ground.

rlhe operator at the manual exchange upon observing the lighted condition of the lamp 50, may insert the plug 6 of the link circuit 3 into the jack 7 of the` trunk `circuit C, whereupon relays 8 and 9 operate in the manner hereiuhcfore described. Relay 1.0 operates upon the actuation of relay 9 and `ing the operator at the manual `phone the talking conductors of the outer section of the trunk circuit, thereby causing the energization of supervisory relay 51` over a circuit from battery through the left-hand Winding of supervisory relay 5l, lower nor- `mal contact of ringing key 47, ring contacts of the plug .45 and the jack 46, righthand vcontact of relay 13, impedence coil 14 (relay l2 having released upon the energization of relay 13), tip contacts of the `jack 46 and the plug 45, upper normal contact of ringing key 47, right-hand Winding of supervisory relay 5l to` ground. Superguishes supervisory lamp 52 which indicates to the toll operator that the operator at the manual oiiice has answered. The toll op-' erator may thereupon actuate listening key complete in any Well known manner, the

Ivisory relay 51 in openingits contact extin` 0 connection with Vthe desired line, after the v necessary instructions rhave been given to the operator at the manual exchange by the toll operator. The respective listening keys may be then restored to normal position.

Shculd the toll operator, for any reason after such connectionas described in the preced-r ing paragraph `has been established desire to` communicate ivith the operator at the manual exchange, this may be done by rst signallThis signaling is etfectedby momentarily and repeatedly actuating the ringing key 47. During each actuation ofthe ringing` key, ringing response relay 54is energized and establishes a short circuit for the high resistance right-hand winding of` relay 9, thereby "reducing ythe rresistance in circuit With supervisory lainp to such an extent that the lainpis lighted over a` circuit from battery through the normal contact of` listening` key 5, contact of supervisory relay 2l, lamp 55, sleeve contacts of the plug 6 and the jack 7, lcftfhand Winding of relay 9 andthe Contact of relay 54 'to ground. 'lhis lighting of the lainp eac-h time relay 54 is 'enengiZed,` results in the intern'iittent lighting or what may bc termed the flashingiof` the supervisory lamp. rflier operator at the manual exchange` upon observing this flashing condition of the supervisory lamp. is informed thereby that the toll operator is recalling. After repeatedly ac.- tuating the ringing key 47 the toll operator may leave the key in its normal position and exchange.

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actuate listening key 53 to connect Ithe telec the telephone set to the circuit so that the operators may converse.

What is claimed is:

l. ln a telephone exchange system, in comoination, a tivo-way trunk circuit comprising a pair of talking conductors terminating in a jack, inductive means connected in and electrically dividing the talking conductors into inner and outer sections, signaling current responsive means connected to the trunk circuit, an impulse response relay, an 1mpulse sending device, means including a link circuit terminating in a plug for connecting bination, two-Way trunk circuit comprising a pair of talking conductors, inductive means connected in and electrically .dividing the -talking conductors into inner and outer sections, signaling current responsive means connected to the trunk circuit, an impulse response relay, an impulse sending device, means including an operators link circuit tor connecting the impulse sending device, With the trunk circuit, a relay bridged across tbe inner section and intermittently energized under control ot the sending device, circuit connections controlled by the bridged relay :tor intermittently bridging the outer section to control the impulse respense relay, an impedance device normally included in the bridge of the outer section, and means controlled by the bridged relay and eti'ective during the intermittent operation thereof for eliminating the impedance device from the bridge and for short circuitingr said signaling current responsive means.

3. In a telephone exchange system, in combinationn a two-Way trunk circuit comprising a pair of talking conductors*y inductive means connected in and electrically dividing the talking conductors into inner and outer sections. signaling current responsive means connected to the trunk circuit, an impulse response relay, an impulse sending device, means including an operators link circuit 'for connecting the impulse sending device nitli the trunk circuit, a relay bridged across the inner section and intermittently energized under control of the sending device. circuit connections controlled by the bridged `relay for intermittently bridging the outer section to control the impulse response relay, an impedance device normally included in the bridge, and a slow release relay energized during the intermittent operation of the bridged relay for removing 4the impedance device from the bridge and ,dividing the talking conductors into inner and outer sections, an operators link circuit, a relayy bridged across the inner section and energizedin response to the connection of the link circuit with the trunk circuit, a normally open bridge including an impedance device for the outer section completed by theenergization of the bridged relay, signaltlie trunk circuit, an impulse sending device connected With the link circuit and causing during its operation the intermittent deenergization of the bridged relay, an impulse response relay controlled by the intermittent opening of the bridge of the outer section in response to the intermittent deenergization of the bridged relay, and a slow release relay energized upon the first deenergization of tbe bridged relay for eliminating the impedance device from the bridge ot the outer section during the intermittent energization of the bridged relay and for short circuiting the signaling current responsive means.

5. In a telephone exchange system, a tivovvay trunk circuit comprising a. pair of talkinav conductors, means for inductively dividing the talking conductors into inner and outer sections, signaling current responsive means connected to the outer section ot said trunk circuit, an operators link circuit having a pair of talking conductors, means responsive to the connection of the link circuit With the trunk circuit for establishing a bridge across the outer section of the trunk circuit, an impulse sender, a key for said link circuit, means responsive to the actuation of said key for rendering the talking conductors of said link circuit discontinuous and for connecting said sender in serial relationship with the talking conductors of the inner-,section of said trunk circuit, and means associated with the inner section of said trunk circuit responsive to the actuation `oi" said sender for intermittently interrupting the bridge across the outer section of said trunk circuit and for eliminating said signaling current responsive means from the trunk circuit.

6. In a telephone exchange system, a tivovvay trunk Circuit comprising a pair of talking conductors. said talking conductors being normally discontinuous, means for inductively dividing the talking conductors into inner and outer sections, signaling current responsive means connected to the inner section of the trunk circuit, an operators link circuit comprising a pair of talking ing current responsive means connected to` conductors, a relay for the trunk circuit energized in response to the connection of the link circuit With the trunk circuit for closing the normally discontinuous talking conductors of the trunk circuit and for disconnecting said signaling current responsive means from the trunk circuit, a second relay bridged across the inner section of said trunk circuit energized in response to the connection of the link circuit With the trunk circuit, a key in said link circuit, an impulse sending device, means responsive to the actuation of said key for rendering the talking conductors of said link circuit discontinuous and for connecting said sender in serial relationship with said bridged relay, and a bridge across the outer section of said trunk circuit controlled by said second relay and said sender.`

7 In a telephone system, a two-Way trunk circuit comprising a pair of talking conductors and a third conductor, means for inductively dividing the talking conductors of the trunk circuit into inner and outer sections, a busy signal and signaling current responsive means associated with the inner section of said trunk circuit, an operators cord circuit, a source of current in said cord circuit, a relay bridged across the inner section of said trunk circuit energized by said source of current in response to the connection of said cord circuit to said trunk circuit, a relay'in the third conductor of said trunk circuit actuated in response to the connection of the cord circuit to the trunk circuit for energizing said busy signal and for disconnecting said signaling current respon-v September 1919.l l

RAND s. BAiLnv. 

